Integrated circuits are widely utilized in electronic equipment and components. Typically, a "device package" assembly (such as, for example, dual in-line for thru-hole mount package assemblies and many surface package assemblies) is utilized to protect the integrated circuit die and associated conductive leads ultrasonically bonded thereto from shock, moisture, light and other environmental factors. In a conventional device package assembly, an integrated circuit die constructed on a semiconductor wafer is encapsulated within and bonded to a protective housing. Conductive microleads are ultrasonically bonded between the die and conductive contacts formed in the device package housing. The device package is sealed to protect the die and leads, and is sold as a stand-alone component in this fashion. In a separate and later manufacturing step, the device package is appropriately mounted on a printed circuit board, and solder joints are formed between the device package conductive contacts and the patterned conductors on the circuit board.
Device packages, while promoting flexibility and convenience for hobbyists and other low volume manufacturing applications, lead to significantly increased assembly costs in high volume manufacturing applications. In high volume applications, it is often the case that identical device packages are repetitively bonded to identical printed circuit boards. Single inline memory modules (SIMMs) and dual inline memory modules (DIMMs), which are incorporated into computer memory components, are examples of such high volume applications. In such repetitive applications, significant time and cost savings could be attained if one were able to eliminate the separate packaging for the integrated circuit die and simply mount the die directly to the printed circuit board. In this manner, unnecessary packaging would be eliminated and assembly could be automated.
Device packages have become standard out of the necessity to protect the sensitive ultrasonically-bonded leads and associated circuitry from a host of damaging environmental factors. In order to mount integrated circuit dies directly to printed circuit boards and remove the necessity for device packages, therefore, an alternative means for protecting the ultrasonically bonded leads from environmental factors is necessary.